An augmented-reality system involves measuring the position of an operator's viewpoint, the direction of the operator's line of sight, and the position of an object in a space. One typical method used in systems for measuring the position and orientation uses a position and orientation measuring device such as FASTRAK (registered trademark) from Polhemus. Another known method uses such a device as a gyroscope to measure only the orientation and measures positional information and orientation drift errors from images.
However, it is usually difficult to match the time at which an image in a physical space was acquired in a conventional augmented-reality system and the time at which the position and orientation measured by the position and orientation measuring device were acquired.
Especially in a method in which an image in a physical space is first captured into a computer and then an image in a virtual space is superimposed on it, there is a time lag between the capture of the physical-space image and the superimposition of the virtual-space image. Therefore, a virtual-space image acquired later than the time of acquisition of a physical-space image is used and accordingly the physical-space image will be misaligned with the virtual-space image. This result in a degradation of the quality of the observer's visual experience of a combination of these images.
In such a case, slightly older measurements may be used to generate a virtual-space image, in order to eliminate misalignment between the physical-space and virtual-space images. However, it has been difficult to determine which past measurements should be used.